Method of developing a high contrast, positive photoresist using a developer containing alkanolamine

ABSTRACT

Compositions and methods for developing quinone diazide positive-working photoresists. The compositions consist essentially of an aqueous solution of a tetraalkylammonium hydroxide and an adjunct having a structure selected from: ##STR1## wherein n is 0 or 1; m is 1 or 2; and each R 1  and R 2  is independently selected from hydrogen, methyl, or ethyl, but in Structure I the two R 2  &#39;s are not both ethyl. The methods involve use of this composition to develop the indicated photoresists. The addition of an adjunct of the indicated type prevents the formation of irregular deposits on the edges of unexposed portions of the photoresist lines when the photoresist is developed. Selection of these adjuncts also increases the uniformity of line widths of photoresist lines developed according to the present invention, and increases the process latitude of the developer.

This is a continuation of co-pending U.S. application Ser. No.07/303,506, filed on Jan. 27, 1989 now abandoned, which in turn is acontinuation-in-part of U.S. application Ser. No. 07/160,639, filed Mar.10, 1988, now abandoned, which in turn is a continuation-in-part of U.S.application Ser. No. 07/035,413, filed Apr. 6, 1987, now U.S. Pat. No.4,808,513.

TECHNICAL FIELD

This invention relates to compositions and processes for developingquinone diazide positive-working photoresists, particularly highcontrast resists used in the fabrication of integrated circuits onsingle-crystal wafers.

BACKGROUND ART

Quinone diazide positive-working photoresists and similarpositive-working compounds used in the preparation of lithographicprinting plates, are described in U.S. Pat. No. 4,464,461, issued toGuild on Aug. 7, 1984 particularly from column 3, line 39 to column 7,line 16. The foregoing patent is hereby incorporated herein byreference. Commercial photoresists of this kind include OFPR-800; otherphotoresists sold by the Dynachem division of Morton Thiokol, Inc.,Tustin, Calif.; and products sold by Shipley Company, Inc., Newton,Mass.; Eastman Kodak Company, Rochester, N.Y.; and others.

A positive-working photoresist functions by being coated on a suitablesubstrate, image-wise exposed to actinic radiation, then subjected to adevelopment process which removes those portions of the photoresistwhich were previously exposed to radiation, leaving the unexposedportions of the resist intact. The developed photoresist patternprotects the corresponding portions of the substrate from a furtheroperation performed on the substrate, such as ion implantation, etching,plating, or the like. (In the case of printing plates, the residualportions of the photoresist have a different affinity for ink than theexposed portions of the substrate.) The known developers for quinonediazide positive-working photoresists comprise an aqueous solution of analkali. The concentration of alkali is chosen to provide a developerwhich will selectively attack the exposed portion of the photoresistunder the exposure and development conditions which have been selected.

While some commercially available developers contain metal salts such assodium carbonate, sodium hydroxide, and others as alkaline agents, theart has recently chosen to avoid metal ion containing alkalinematerials, or other metal ion sources, in photoresist developers. Aconcern has developed that residual metal ions left by the developermight form conductive paths in the finished device. Because of thisavoidance of metal ion containing developers, the preferred alkalinematerials are tetraalkylammonium hydroxides, and particularlytetramethylammonium hydroxide (TMAH). TMAH based developers arediscussed in U.S. Pat. No. 4,423,138, issued to Guild on Dec. 27, 1983;U.S. Pat. No. 4,464,461, issued to Guild on Aug. 7, 1984; EuropeanPatent Application 0,062,733, filed by Cawston et al on Jan. 28, 1982and published on Oct. 20, 1982, based on a corresponding U.S. patentapplication filed Apr. 10, 1981; Grieco et al, "Photoresist DeveloperCompounds", IBM Technical Disclosure Bulletin, Volume 13, Number 7(December, 1970); "Improved Resist Developer," Research Disclosure22713, March, 1983, pages 98-99; and others.

Several prior patents show the possibility of using morpholine or analkanolamine, particularly ethanolamine, in photoresist developers.According to its English language abstract, Japanese patent application59.119105, believed to have been published Dec. 26, 1985, teaches theuse of either an inorganic alkali or an organic amine such asmonoethanolamine or ethylenediamine as an alkaline agent in aphotoresist developer. U.S. Pat. No. 4,464,461, column 1, lines 40-43,indicates that developers containing, for example, alkanolamines are"well known". U.S. Pat. No. 4,530,895, issued to Simon et al on July 23,1985, at column 1, lines 59-62, suggests use of a developer containingan alkaline substance such as diethylamine, ethanolamine, ortriethanolamine as a photoresist developer. U.S. Pat. No. 4,411,981,issued to Minezaki on October 25, 1983, discloses from column 3, line 46to column 4, line 8, the use of a developing and etching solution for aphotoresist containing various organic bases such as TMAH,monoethanolamine, diethanolamine, or triethanolamine, among many otherbasic reacting compounds. The Minezaki patent also discloses aphotoresist developer in column 5, lines 10-16, and Table 3 comprisingan aqueous solution of 5% TMAH, 1-2% morpholine, 0.04% coumarin, about0.1% of an unspecified surfactant, and the balance water. Minezakistates this composition is diluted double or triple with distilled waterto provide a developing and etching solution. The ratio of TMAH tomorpholine is from 1:0.4 to 1:0.2 in this composition. None of thesereferences suggests any reason to mix a quaternary ammonium compound andan alkanolamine or morpholine to correct any shortcoming of eithermaterial used alone as a developer.

As will be shown in comparative examples, TMAH used alone as aphotoresist developer causes what appears to be a deposit of flakyresidue along the upper and lower edges of lines of developerphotoresists, particularly high contrast photoresists. The presence ofthis residue in exposed areas (which are intended to be free ofphotoresist) suggests potential problems.

Alkanolamines by themseleves are not (suitable as developers for highcontrast photoresists of the type exemplified herein, as they developlines with poor resolution, fail to develop them altogether, or stripthe photoresist. High concentrations of these developers also roughenthe upper, normally smooth surface of developed photoresist lines.

One continuing challenge, as circuit geometries shrink and qualitystandards are maintained or raised, is how to maximize line widthuniformity. Good line width uniformity means that lines of developedphotoresist have nearly the same nominal line width and other dimensionsas the mask lines and that these dimensions don't vary significantlydepending on the location of the line on the wafer, the location of thewafer in a boat in which a batch of wafers are immersion processedtogether, or the order in which wafers are spray processed.

Another continuing challenge in photoresist developer research is how toachieve the desired line width uniformity despite variations from thenominal conditions selected for development. A developer compositionwhich achieves this is said to have wide process latitude.

It is further desirable that a photoresist developer not cause the sidewalls of the developed photoresist to become less vertical (sloped).

SUMMARY OF THE INVENTION

One object of this invention is to solve the residue problem of TMAH orsimilar photoresist developers while retaining or improving the linewidth uniformity and wide process latitude of such developers. A furtherobject is to accomplish the preceding object with a developer which isusable in commercial automated equipment, especially ray equipment whichdemands that a developer be easily sprayable.

A first aspect of the invention is a composition for developing anexposed, quinone diazide, positive-working photoresist. The compositionconsists essentially of an aqueous solution of an alkali which alsocontains an adjunct. The alkali is a tetraalkylammonium hydroxide, andis present in the composition in an amount sufficient to enable thecomposition to develop the photoresist. The adjunct has a structureselected from: ##STR2## In the above structures, n is 0 or 1; m is 1 or2; and each R¹ and each R² is independently selected from hydrogen,methyl, or ethyl (except that in Structure I both R² moieties cannot beethyl). If m is 2 (representing the presence of a quaternary nitrogenatom), each R¹ attached to the nitrogen atom is selected independently.

This adjunct is present in the composition in an amount sufficient toreduce formation of the previously mentioned irregular deposits on theedges of unexposed portions of the photoresist during development of thephotoresist. The amount of the alkali and the adjunct to be used can bevariously expressed to accomplish different objectives. For one example,the adjunct can be present in an amount sufficient to increase the C_(p)value of the composition, as defined later in this specification. Foranother example, the adjunct can be present in an amount sufficient toincrease the process latitude of the composition, as defined later inthis specification.

In a preferred aspect of the invention, about 0.7 to about 1.6% byweight of the tetraalkylammonium hydroxide is present, and the ratio ofthe hydroxide to the adjunct is less than or equal to about 1:3 byweight. The composition can optionally contain from about 0 to 0.05% byweight of a surfactant to improve the sprayability of the compositionand to avoid the problem of dewetting the resist during development.

A second aspect of the invention is a method for developing an exposedquinone diazide positive-working photoresist without forming irregulardeposits on the edges of unexposed portions of the photoresist. Themethod comprises the steps of providing an exposed photoresist fordevelopment; providing the developer previously defined above;developing the photoresist with the indicated developer until thepattern is cleared; and rinsing the developer from the photoresist.

Still another aspect of the invention is a similar method in whichenough of the previously stated adjunct is present in a developer toprovide a C_(p) value of at least about 1.33 for the developer as usedto develop a quinone diazide positive-working photoresist.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 through 6 are each a perspective fragmentary photographic viewof a developed two micron (nominal mask dimension) photoresist line,also illustrating the surrounding substrate and a portion of theadjacent line. Each photograph was taken at a magnification of 20,000diameters, at an energy of 23 KV, using a scanning electron microscope.FIGS. 1 through 6 show lines developed according to Examples 36 through41, respectively. FIG. 6 represents the state of the art prior to thepresent invention, and FIG. 5 shows development using an adjunct notwithin the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Photoresist developers according to the present invention consistessentially of a solvent, an alkali, an adjunct as defined above, andoptionally a surfactant and various other minor ingredients.

While various organic solvents are used in some photoresist developers,for the present purpose the preferred solvent is deionized water. Theamount of water used is dictated by the amount of other ingredients.While the amount of water is not generally critical, the compositionsdescribed herein contain from about 60% to about 94% by weight water.

The alkali is the primary ingredient which dissolves exposed portions ofthe photoresist when the photoresist is developed. Varioustetraalkylammonium hydroxides have been used or suggested as suitablealkaline compounds; the use of any of these well known compounds iscontemplated in the broadest aspect of the present invention. (As usedherein in the context of tetraalkylammonium hydroxides, "alkyl" does notinclude alkanol moieties.) The most common alkali is tetramethylammoniumhydroxide (TMAH).

The amount of alkali useful herein is most broadly more than 0.5% byweight, preferably from about 0.7 to about 2% by weight, more preferablyfrom about 0.8 to about 1.6% by weight, and most preferably from about0.9 to about 1.1% by weight. The amount of alkali used in a particularformulation must be adjusted to account for the influence of the otheringredients, particularly the adjuncts, which are also alkaline.

The adjuncts useful herein are those specified previously in theSummary. Table I recites all the adjuncts within the previously statedStructure I wherein each R² is hydrogen. Adjuncts within Structure I inwhich one or both R² moieties are methyl or ethyl, preferably methyl(but excluding a structure in which both R² 's are ethyl), are alsocontemplated herein. Adjuncts within structure I are also calledalkanolamines herein. Adjuncts within Structure II contemplated hereininclude morpholine.

As the comparative examples provided below will illustrate, severalcompounds structurally related to the adjuncts specified above eitherinterfere with the development process or do not provide the benefits ofthe present invention. Thus, diols such as propylene glycol; diaminessuch as ethylenediamine; and di- or trialkanolamines have been found notto be useful herein.

The preferred adjuncts are species 1, 2, and 10 as stated in Table I anddimethyl-3-amine-1-propanol (DMAP). These adjuncts are all suitable forphotoresist development by immersion. Most preferred is species 10,which has also been found to be suitable for spray development ofphotoresists.

The proportion of adjunct contemplated herein is determined largely bythe ratio of the alkali to the adjunct by weight. (A lower ratioindicates less TMAH in relation to the amount of the adjunct.) For spraydevelopment this ratio is no more than 1:9, preferably 1:12 to 1:38, andmost preferably about 1:15 if the adjunct is 1-hydroxy.3.amino-propane.For immersion development the ratio can be as great as 1:3. The lowerlimits are provided in the preferred range of ratios because when theindicated maximum proportion of adjunct is exceeded, the surfaces ofdeveloped lines will be roughened. The upper limits of the ranges ofratios are specified to provide a noticeable reduction in the amount ofresidue formed. The most preferred ratios have been found to minimizethe residue problem at minimal cost while avoiding the roughening effectof excess adjunct. These ratios will be found to vary with theproportion and selection of alkali, the choice of a particular adjunct,and the choice of immersion or spray development.

The desired amount of adjunct will typically be from about 4% to about40% by weight of the composition. A preferred range is from about 14% toabout 21% by weight.

The present compositions may optionally contain a surfactant, inparticular a nonionic surfactant, to improve the sprayability andwetting properties of the formulation. In some spray developmentequipment, some of the present compositions will emerge from the spraynozzle as a cohesive stream of fluid, rather than as finely atomizeddroplets. The result can be that the developer is not adequatelydistributed during the spray step. The addition of certain adjuncts,particularly in large amounts, has been found to reduce the sprayabilityof the compositions. This effect is believed to result from changes inthe viscosity or the surface tension of the compositions.

Another fault which some of the present developers have is a tendency todewet, or withdraw from, the photoresist pattern during development.This reduces the amount of time the photoresist pattern is exposed tothe developer, and thus inhibits development. The presence of a nonionicsurfactant alleviates this problem too.

The preferred nonionic surfactants are the polyethylene oxidecondensates of alkyl phenols. These compounds include the condensationproducts of alkyl phenols having an alkyl group containing from about 6to 12 carbon atoms, in either a straight chain or branched chainconfiguration, with ethylene oxide in amounts equal to 5 to 25 moles ofethylene oxide per mole of alkyl phenol. The alkyl substituent in suchcompounds can be derived, for example, from polymerized propylene,diisobutylene, octene, or nonene. Examples of compounds of this typeinclude nonylphenol condensed with about 9.5 moles of ethylene oxide permole of nonylphenol, dodecyl phenol condensed with about 12 moles ofethylene oxide per mole of phenol, dinonyl phenol condensed with about15 moles of ethylene oxide per mole of phenol, and diisooctylphenolcondensed with about 15 moles of ethylene oxide per mole of phenol. Oneparticular surfactant which has proven useful herein is TRITON X-100,marketed by Rohm and Haas Co., Philadelphia, Pa. The useful amount ofsurfactant is limited by the tendency of such surfactants to degrade theoptimal vertical wall structure of the developed lines of photoresist,causing sloping. The preferred composition, therefore, contains no morethan about 0.05% by weight of a nonionic surfactant. Some compositionsrequire no surfactant at all.

Other components, such as preservatives for TMAH, dyes, wetting agents,cosolvents, buffers, and the like may be added to developers accordingto the present invention. The preferred additives are essentially freeof metal cations.

For purposes of the present specification, the amount of alkalieffective to develop the photoresist is determined experimentally byproviding a proposed composition and varying the amount of alkali tofind a concentration which will develop the photoresist withoutstripping it. The necessary amount of alkali will be determined by manyfactors, including the presence of an adjunct and any other alkalineconstituents of the developer; exposure energy; line geometries;development mode and conditions; and temperature. The examples in thisspecification provide specific compositions which have been found toperform well. One of ordinary skill in the art can readily formulate adeveloper having an appropriate amount of alkali to develop a particularphotoresist.

Similarly, the amount of the adjunct which is sufficient to reduceformation of irregular deposits on the edges of unexposed portions ofthe photoresist during development will depend on the developerformulation, process conditions, the photoresist used and how it isapplied, and other factors. An amount of adjunct sufficient to reduceformation of irregular deposits is determined qualitatively by examiningscanning electron microscope photomicrographs of photoresists developedwith various developers to select the optimal developer for a giventask. When the amount of the adjunct is expressed as an amountsufficient to increase the C_(p) value of the composition, C_(p) valuesof the composition under the desired development conditions aremeasured. The amount of adjunct is adjusted to maximize the C_(p) valueunder the desired development conditions of at least about 1.33 when onemicron lines are developed.

If the amount of adjunct is expressed as an amount sufficient toincrease the process latitude of the composition, process latitudevalues of the composition are measured. The amount of adjunct isadjusted to maximize the process latitude in a particular formulation.Preferred compositions provide a process latitude of at least about 1.33under the development conditions specified in the Examples.

It is not evident from any prior art known to the inventors thatselection of the present developer compositions will allow a photoresistto be developed under high contrast conditions without forming irregulardeposits on the edges of unexposed portions of the photoresist,providing a C_(p) value and a process latitude for the developer of atleast about 1.33.

Various modes of development are contemplated within the scope of thepresent invention. In immersion development, the coated and exposedwafers, either alone or in a boat of wafers, are supported in a bath ofthe selected developer for a sufficient time to develop thephotoresists. In spray process development individual wafers coated withthe photoresist are transported to a development site and developed byone or more operations such as streaming the developer onto the surfaceof the photoresist; spinning the wafer to remove excess material,particularly fluid, from its surface; spraying the developer over a widesurface of the wafer; and puddling, which is done by allowing residualdeveloper to remain as a meniscus or puddle covering the surface of thestationary wafer. Automated spray development equipment can beprogrammed to provide the desired selection and sequence of developmentsteps to develop each wafer.

EXAMPLES

The following examples are provided to illustrate practice of thepresent invention, including the best mode. The claims, and not theexamples, define the scope of the present invention.

Photoresist samples were prepared as follows. The substrate was asilicon wafer with a polyoxide surface coating, pre-treated withhexamethyldisilane to promote adhesion. EPR-5000, a novolak resin-basedcomposition sold by the Dynachem division of Morton Thiokol, Inc.,Tustin, Calif., was coated onto the substrate using conventionalautomated spin-coating equipment. The coating thickness was about 13,000Angstroms (1.3 microns), plus or minus about 300 Angstroms, and wasmeasured for each wafer individually. The coatings were dried andconditioned in the usual manner, providing sensitized substrates typicalof those used in the industry.

For all experiments, the sensitized substrates were exposed through anexposure mask on a step-and-repeat exposure tool with ultravioletradiation provided by a high pressure mercury vapor lamp. The size ofthe exposed image (24 millimeters by 14 millimeters) allowed severalexposures (118 or less) to be distributed on the surface of thesubstrate without overlapping. It was possible either to incrementallyincrease exposure energies at each exposure, or to repeat one exposureenergy several times across the surface of the substrate.

Developer solutions were prepared by mixing the ingredients recitedbelow to provide one-gallon batches.

In the immersion testing, an entire batch of each developer solution waspoured into a large dish, forming a bath deep enough to completelyimmerse a wafer being developed. The exposed substrates were developedby manually immersing each one in the dish of developer. The immersiontime was one minute 60 seconds). Then, the substrates were removed fromthe dish of developer and rinsed by placing them in a cascade tank fedfrom the bottom with deionized water.

For spray/puddle development testing the development and rinsing stepswere performed using conventional automated spray development equipmentsold by Silicon Valley Group, San Jose, Calif. In each program severalsteps were completed sequentially. For each step, the wafer was rotatedat the indicated rate while the indicated material was applied in theindicated manner for the indicated amount of time, according to one ofthe schedules in Table II.

Film speed of the developer was evaluated by observing through anoptical microscope at 400X magnification which of several developed onemicron lines of resist, representing different doses of radiation, wereresolved.

Linewidth uniformity (Critical Dimension Uniformity) is evaluated usingseveral exposures at the same dose across the surface of the substrate.Linewidth measurements are made at each of these exposures, themeasurements are averaged, and the standard deviation is calculated. Avalue called "C_(p) " can be calculated from this data according to thefollowing formula: ##EQU1## Delta L is the difference between theminimum and maximum acceptable linewidths of a line defined in thephotoresist by a 1 micron line on the exposure mask. Sigma is onestandard deviation.

For a 1 micron nominal linewidth, the acceptable range of linewidths isdefined to be from 0 9 to 1.1 microns; delta L is thus (1.1-0.9)microns, or 0.2 microns. An acceptable value of sigma is defined hereinto be less than or equal to 0.025 microns. Presenting the sameinformation in terms of the C_(p), an acceptable value for C_(p) isdefined herein to be less than or equal to 1.33 microns.

Process latitude is a measure of a developer's ability to functionsatisfactorily despite defined variations in process parameters. Forpresent purposes process latitude is satisfactory if, at exposureenergies of from 250 to 150 mJ/cm² ; a resist thickness of 1.3 microns(plus or minus 0.1 microns) of EPR-5000 resist; a (resist) soft baketemperature of from 110° C. to 120° C.; a developer temperature of 19°C. (plus or minus 1° C.); and an exposure tool focus on the top of theresist (plus or minus 1.0 microns); C_(p) exceeds 1.33 microns. Processlatitude can be reported quantitatively as the minimum value of C_(p)over the defined range of exposure energies. The developers according tothe present invention have better process latitude than conventionalresists which do not contain adjuncts.

In Examples 1-4, monoethanolamine, abbreviated "MEA", was used as anadjunct according to the present invention. The proportions ofingredients and other information are set out in Table III. In theTables, development mode "I" indicates immersion development. "Spray 1"indicates spray development according to Program: 1 set forth in TableII. The abbreviation "mJ/cm² " indicates the radiation exposure inmillijoules per square centimeter. "Result" provides a qualitativeindication of the result of the experiment. LR indicates low resolutionor a lack of resolution, meaning that the developer did not selectivelyremove the exposed portions of the photoresist while refraining fromattacking the unexposed portions thereof. "Poor spray" means that thecomposition was not properly atomized by the spray nozzle. "Poordevelop" means that exposed portions of the photoresist were not removedor were removed inadequately. The "ratio" is a recapitulation of theratio of TMAH to the adjunct, here MEA, providing a ready comparison ofthe development result with the ratio of these ingredients.

Looking at Table III, it will be evident that examples 1 and 2 providegood development in an immersion mode, while in Example 3 the spraypattern provided during spray development was considered poor,indicating that the material was developed but that irregulardevelopment is potentially present. Example 4, in which only 0.5% TMAHand 80.0% MEA is employed as a developer, demonstrates that this is toolittle TMAH to provide proper development, even in the presence of 80%monoethanolamine. Example 4 also establishes that monoethanolamine byitself, even at high concentrations, is not a suitable developer for thepresent photoresist.

Table IV, in which the adjunct is 1-amino-2-hydroxypropane (species 2 ofTable I, identified in Table IV as 1,2-MPA), shows the results ofExamples 5-8. In this Table and subsequent Tables, "X-100" indicatesTRITON X-100 nonionic surfactant, identified previously in thespecification. "Spray 2" in the development mode line indicates SprayDevelop Program 2 in Table II. In the result column "res." indicatesthat a residue was present on the edges of developed liens of thephotoresist.

1-amino-2-hydroxypropane sometimes provides a residue (Examples 5 and 8and sometimes does not (Examples 6 and 7). It is better for immersiondevelopment than for spray development; a poor spray pattern was notedduring spray development. The best result is obtained at a ratio of 1:18as in Example 7, in which no residue was noted on the developed lines.

Examples 9.19 in Tables V and VI show development with1-amino-3-hydroxypropane, abbreviated in Tables V and VI as 1,3-MPA.This is species 10 of Table I. Looking first at Table V, Examples 9 and10 are essentially identical spray development runs, but in Example 9 aresidue was noted at a ratio of 1:12, while in Example 10 no residue wasnoted. This indicates that this is a marginally acceptable formulationfor spray development. Similarly, Examples 11 and 12 are essentiallyidentical spray development runs. In one case a residue was provided,and in the other case no residue was observed. Examples 9-12 were allrun at a ratio of 1:12, which therefore is less preferred for spraydevelopment than the 1:15 ratio of Example 13. A 1:15 ratio has beenfound in this and other examples of spray development to almost neverleave residue on the edges of the developed resist lines. Thus, a ratioof 1:15 is preferred to provide optimal spray development with minimalamounts of the alkanolamine.

Examples 14-19 show ratios of TMAH to 1,3-MPA of 1 to 3 or lowersuccessfully used according to the present invention. Examples 14-16,using spray development, illustrate that the 1:15 composition of 1,3-MPAcan be sprayed successfully and provides residue free development. Thecompositions of Examples 14-16 all contain TRITON X-100 surfactant, inincreasing amounts. In Example 16 0.05% of this surfactant was too much,as it caused developed resist line sidewalls to slope or otherwisedeviate from the optimal vertical sidewalls. Thus, 0.05% of thissurfactant is more than the preferred maximum amount under the otherconditions of this example.

Examples 17, 18, and 19 illustrate the operability of ratios as high as1:3 and as low as 1:37.9 for immersion development. Example 19illustrates that at extremely low ratios, even when the amount of TMAHis minimized, the developed resist has a rough surface. Roughness isbelieved to be caused by the presence of a large amount of the adjunct.While some roughness can be tolerated, it is not desirable, so a minimumratio of about 1 to 38 is preferred herein.

Tables VII, VIII, and IX embody the results of comparative Examples20-35, using various similar compounds in place of the adjuncts of thepresent invention.

In Table VII, Examples 20-24, the alkanolamine was replaced withethylene diamine (abbreviated EDA in the table) in ratios of from amaximum of 1:3 to a minimum of 1:37.8. In all cases immersiondevelopment was used. The relatively large proportion of TMAH in thehigh ratio of Example 20 stripped both developed and undevelopedportions of the resist from the substrate. The remaining examples allshow the formation of residue or heavy residue, and the lowest ratio ofTMAH (and highest ratio of EDA) provides a heavy residue and lack ofresolution which do not constitute suitable development. The inventorsconclude from this example that a wide range of different proportionsand ratios of ethylene diamine does not exhibit the beneficialproperties of the present invention.

Table VIII provides comparative examples 25-29 in which the adjunct isreplaced with ethylene glycol (EG). Over a wide range of ratios andproportions of ethylene glycol, the result is again a residue on thedeveloped lines of photoresist, in either the immersion or the spraymode of development. Example 29 is prior art, and illustrates that aformulation containing just TMAH in a proportion sufficient to developthe photoresist provides a residue, and thus is not an optimal developeraccording to the present invention. As noted previously, Example 4 showsthe contrary situation in which a large amount of an alkanolamineaccording to the present invention is present (80%) and an insufficientproportion of TMAH is present. Comparing these examples, it is evidentthat neither TMAH alone nor an alkanolamine alone provides properdevelopment, but the other examples show that the combination of thesetwo ingredients improves development unexpectedly.

In Table IX, Examples 30 and 31 show the use of diethanolamine(abbreviated: DEA); comparative Examples 32 and 33 show the use oftriethanolamine (abbreviated: TEA); and comparative examples 34 and 35employ diethylethanolamine (abbreviated: DEEA) in place of the presentadjuncts. In all these comparative examples, each in two differentproportions employing the immersion development mode, development washindered by the additive. In Examples 30-33, despite a high maximumexposure, only a latent image was produced. This means that the exposedportions of the photoresist were not removed by this formulation. InExamples 34 and 35 the developed and undeveloped portions of thephotoresist were both stripped.

The comparative examples illustrate that the class of additives whichprevent residue formation without disturbing the function of the resistdeveloper is narrow. Ethylene diamine differs from the adjunctmonoethanolamine by substitution of a second amine for a hydroxy group.Ethylene glycol of comparative Examples 25-29 is different frommonoethanolamine only in that a second hydroxyl group is substituted forthe amine group. In short, a structure with an amine group on one endand hydroxyl group on the other works, but respective structures withtwo amine groups or two hydroxyl groups in the same positions do notwork. The additives of comparative examples 30-35 differ from thepresent adjuncts, and specifically from monoethanolamin, because twoethyl or ethanol moieties are substituted for the amine hydrogen atomsof the present generic formula. Diethanolamine has two ethanol moietiesinstead of the single ethanol moiety of monoethanolamine according tothe present invention. Triethanolamine has three ethanol moieties inplace of the single ethanol moiety of the present invention.Diethylethanolamine has two ethyl groups in place of the amine hydrogensof monoethanolamine. These substitutions provide compounds which do notfunction in the advantageous manner of the resent adjuncts.

The formulations and data for Examples 36-41 are reported in Table X.Exemplary two micron lines of each developed resist were photographedwith a scanning electron microscope at a magnification of 20,000diameters and an energy of 23 KV. FIGS. 1 through 6 respectivelycorrespond to Examples 36 through 41.

In FIG. 1 and Example 36, the developer contained1-amino-2-hydroxypropane at a ratio of 1:12. FIG. 1 illustrates someresidue, particularly along the upper edges of the resist, but noroughness. (The slight roughness or grain shown in the photographs onthe top surface of each resist line and on the substrate between theresist lines is a combination of noise in the micro. scope andphotographic grain.) FIG. 1 shows a reduction of the residue problem,but not a complete solution.

In FIG. 2 and Example 37, the formulation contained the adjunct1-amino-3-hydroxypropane at a ratio of 1:12. The result shown in FIG. 2is similar to that shown in FIG. 1.

In FIG. 3 and Example 38, a 1:15 ratio of 1-amino-3-hydroxypropane wasused; the formulation contained 1.00% of TMAH. As FIG. 3 shows, thedeveloped lines have smooth upper surfaces and no visible residue. (Theregular, horizontal striations on the sidewalls of the lines areartifacts of standing waves in the exposure radiation, and are notresidue.)

In Example 39 and FIG. 4, the ratio of TMAH to 1-amino-3-hydroxypropaneis 1:37.9. The line is clearly developed and has no residue, but theentire top and side surfaces of the line are roughened; this isconsidered less than optimal development, although the advantages of thepresent invention other than absence of roughness are obtained in thisexample.

In Example 40 and FIG. 5, ethylene diamine is added to the developer ata ratio of 1:20. Heavy residue is present on the edges of the topsurface. The vertically oriented ridge-and-valley irregularity of thesidewalls is also related to the presence of the residue problem.

Example 41 and FIG. 6 illustrate development with a prior artformulation of 2.0% by weight TMAH and no other additives. FIG. 6 thusillustrates that without an adjunct a heavy residue is observed.

In Table XI, adjuncts other than the alkanolamines of Table 1 were usedaccording to the present invention. In Example 42, a developercontaining morpholine was used successfully. No residue was noted,although the developed lines had a roughened surface. DMAP(dimethyl-3-amino-1-propanol) was successfully used in Example 43, andneither residue nor roughened surfaces were observed.

                  TABLE I                                                         ______________________________________                                        Alkanolamine Adjunct Species                                                  Species #    Name                                                             ______________________________________                                         1           1-amino-2-hydroxyethane                                           2           1-amine-2-hydroxypropane                                          3           1-amino-2-hydroxybutane                                           4           1-hydroxy-2-aminopropane                                          5           2-amino-3-hydroxybutane                                           6           2-amino-3-hydroxypentane                                          7           1-hydroxy-2-aminobutane                                           8           2-hydroxy-3-aminopentane                                          9           3-amino-4-hydroxyhexane                                          10           1-amino-3-hydroxypropane                                         11           1-amino-3-hydroxybutane                                          12           1-amino-3-hydroxypentane                                         13           1-amino-2-methyl-3-hydroxypropane                                14           1-amino-2-methyl-3-hydroxybutane                                 15           1-amino-2-methyl-3-hydroxypentane                                16           1-amino-2-ethyl-3-hydroxypropane                                 17           2-hydroxy-3-aminomethylpentane                                   18           3-aminomethyl-4-hydroxyhexane                                    19           1-hydroxy-3-aminobutane                                          20           2-amino-4-hydroxypentane                                         21           2-amino-4-hydroxyhexane                                          22           2-amino-3-hydroxymethylbutane                                    23           2-amino-3-methyl-4-hydroxypentane                                24           2-amino-3-methyl-4-hydroxyhexane                                 25           2-amino-3-hydroxymethylpentane                                   26           2-amino-3-(1-hydroxyethyl)-pentane                               27           3-hydroxy-4-(1-aminoethyl)-hexane                                28           1-hydroxy-3-aminopentane                                         29           2-hydroxy-4-aminohexane                                          30           3-amino-5-hydroxyheptane                                         31           2-hydroxymethyl-3-aminopentane                                   32           2-hydroxy-3-methyl-4-aminohexane                                 33           3-amino-4-methyl-5-hydroxyheptane                                34           3-amino-4-hydroxymethylhexane                                    35           2-hydroxy-3-ethyl-4-aminohexane                                  36           3-amino-4-ethyl-5-hydroxyheptane                                 ______________________________________                                    

                  TABLE II                                                        ______________________________________                                        Spray Development Programs                                                           Wafer       Material         Duration                                  Step   Rotation    Applied    Mode  of Step                                   ______________________________________                                        Spray Develop Program 1                                                       1        50 rpm    Developer  Spray 42 sec.                                   2      1,000 rpm   DI water   Stream                                                                              10 sec.                                   3      4,000 rpm   None       Dry   10 sec.                                   Spray Develop Program 2                                                       1      1,000 rpm   DI water   Stream                                                                               2 sec.                                   2      1,000 rpm   Developer  Spray 10 sec.                                   3        400 rpm   Developer  Spray  5 sec.                                   4         0 rpm    Developer  Spray  2 sec.                                   5         0 rpm    None       Puddle                                                                              15 sec.                                   6      1,000 rpm   DI water   Stream                                                                              10 sec.                                   7      4,000 rpm   None       Dry   10 sec.                                   Spray Develop Program 3                                                       1        450 rpm   Developer  Spray  7 sec.                                   2        50 rpm    Developer  Spray  4 sec.                                   3         0 rpm    None       Puddle                                                                              15 sec.                                   4        50 rpm    Developer  Spray  4 sec.                                   5         0 rpm    None       Puddle                                                                              15 sec.                                   6        50 rpm    Developer  Spray  4 sec.                                   7         0 rpm    None       Puddle                                                                              15 sec.                                   8      1,000 rpm   DI water   Stream                                                                              10 sec.                                   9      5,000 rpm   None       Dry   10 sec.                                   ______________________________________                                    

                  TABLE III                                                       ______________________________________                                        MEA, Examples 1-4                                                             Component   1       2         3     4                                         ______________________________________                                        Wt. % TMAH  1.60    1.00      1.00  0.50                                      Wt. % MEA   12.5    37.9      37.9  80.0                                      Wt. % H.sub.2 O                                                                           85.9    61.1      61.1  19.50                                     Total %     100.00  100.00    100.00                                                                              100.00                                    Development I       I         spray I                                         Mode                                                                          mJ/cm.sup.2 70      50        50    100                                       Result      good    good      poor  LR;                                                                     spray poor                                                                          develop                                   Ratio       1:7.8   1:37.9    1:37.9                                                                              1:160                                     ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                        1,2-MPA, Examples 5- 8                                                                  5      6       7        8                                           ______________________________________                                        Wt. % TMAH  1.25     1.25    1.00   1.05                                      Wt. % 1,2-MPA                                                                             15.0     15.0    18.0   21.0                                      Wt. % X-100 --       --      --     0.01                                      Wt. % H.sub.2 O                                                                           83.75    83.75   81.00  77.94                                     Total %     100.00   100.00  100.00 100.00                                    Development I        spray 2 I      spray 2                                   Mode                                                                          mj/cm.sup.2 60       70      50     70                                        Result      res.     poor    good   res. and                                                       spray          poor spray                                Ratio       1:12     1:12    1:18   1:20                                      ______________________________________                                    

                  TABLE V                                                         ______________________________________                                        1,3-MPA, Examples 9- 13                                                                 9     10      11      12    13                                      ______________________________________                                        Wt. % TMAH  1.20    1.20    1.20  1.20  0.96                                  Wt. % 1,3-MPA                                                                             14.4    14.4    14.40 14.40 14.40                                 Wt. % X-100 --      --      .01   .01   .01                                   Wt. % H.sub.2 O                                                                           84.40   84.40   84.39 84.39 84.63                                 Total %     100.00  100.00  100.00                                                                              100.00                                                                              100.00                                Development spray   spray   spray spray spray                                 Mode        2       2       2     2     1                                     mj/cm.sup.2 60      60      80    70    190                                   Result      res.    good    res.  good  good                                  Ratio       1:12    1:12    1:12  1:12  1:15                                  ______________________________________                                    

                  TABLE VI                                                        ______________________________________                                        1,3 MPA, Examples 14- 19                                                             14    15      16      17    18    19                                   ______________________________________                                        Wt. %    1.00    1.10    1.10  1.60  0.95  0.70                               TMAH                                                                          Wt. %    15.0    16.5    16.5  4.80  19.0  26.53                              1,3-MPA                                                                       Wt. % X-100                                                                            .005    .01     .05   --    --    --                                 Wt. % H.sub.2 O                                                                        83.995  82.39   82.35 93.60 80.05 72.77                              Total %  100.00  100.00  100.00                                                                              100.00                                                                              100.00                                                                              100.00                             Development                                                                            spray   spray   spray I     I     I                                  Mode     1       1       1                                                    mJ/cm.sup.2                                                                            110     60      70    120   50    50                                 Result   good    good    side- good  good  rough                                                       wall                                                                          slope                                                Ratio    1:15    1:15    1:15  1:3   1:20  1:37.9                             ______________________________________                                    

                  TABLE VII                                                       ______________________________________                                        Comparative Examples 20- 24                                                   Component   20      21      22    23    24                                    ______________________________________                                        Wt. % TMAH  3.0     1.65    1.05  0.84  0.90                                  Wt. % EDA   9.0     4.95    12.6  17.4  34.02                                 Wt. % H.sub.2 O                                                                           88.0    93.40   86.35 81.76 65.08                                 Total %     100.00  100.00  100.00                                                                              100.00                                                                              100.00                                Development I       I       I     I     I                                     Mode                                                                          mJ/cm.sup.2 10-110  50      50    50    60                                    Result      strip   res.    res.  res.  heavy                                                                         res.;                                                                         LR                                    Ratio       1:3     1:3     1:12  1:20  1:37.8                                ______________________________________                                    

                  TABLE VIII                                                      ______________________________________                                        Comparative Examples 25- 29                                                   Component   25      26      27    28    29                                    ______________________________________                                        Wt. % TMAH  2.40    2.55    0.87  0.90  2.2                                   Wt. % EG    7.20    30.6    17.40 34.02 --                                    Wt. % H.sub.2 O                                                                           90.40   66.95   81.73 65.08 97.8                                  Total %     100.00  100.00  100.00                                                                              100.00                                                                              100.00                                Development I       I       spray spray I                                     Mode                        2     2                                           mJ/cm.sup.2 60      80      70    50    50                                    Result      res.    res.    res.  heavy res.                                                                    res.                                        Ratio       1:3     1:12    1:20  1:37.8                                                                              --                                    ______________________________________                                    

                  TABLE IX                                                        ______________________________________                                        Comparative Examples 30- 35                                                   Component                                                                              30      31      32    33    34    35                                 ______________________________________                                        Wt. %    1.00    1.00    1.00  1.00  1.00  1.00                               TMAH                                                                          Wt. % DEA                                                                              10.00   20.00   --    --    --    --                                 Wt. % TEA                                                                              --      --      10.00 20.00 --    --                                 Wt. %    --      --      --    --    10.00 20.00                              DEEA                                                                          Wt. % H.sub.2 O                                                                        89.00   79.00   89.00 79.00 89.00 79.00                              Total %  100.00  100.00  100.00                                                                              100.00                                                                              100.00                                                                              100.00                             Develop- I       I       I     I     I     I                                  ment                                                                          Mode                                                                          mJ/cm.sup.2                                                                            400     400     400   400   --    --                                 Result   latent  latent  latent                                                                              latent                                                                              strip strip                                       image   image   image image                                                   only    only    only  only                                           Ratio    1:10    1:20    1:10  1:20  1:10  1:20                               ______________________________________                                    

                  TABLE X                                                         ______________________________________                                        Examples 36- 41                                                               Component                                                                              36      37      38    39    40    41                                 ______________________________________                                        TMAH     1.25    1.20    1.00  0.70  0.84  2.0                                1,2-MPA  15      --      --    --    --    --                                 1,3-MPA  0       14.40   15.0  26.53 --    --                                 EDA      0       --      --    --    16.8  --                                 X-100    0       .01     .01   --    --    --                                 H.sub.2 O                                                                              83.75   84.39   83.99 72.77 82.36 98.00                              Total %  100.00  100.00  100.00                                                                              100.00                                                                              100.00                                                                              100.00                             Develop- spray   spray   spray spray I     spray                              ment     2       1       2     3           2                                  Mode                                                                          mJ/cm.sup.2                                                                            70      60      110   50    50    90                                 Result   res.    slight  good  rough heavy heavy                                       poor    res.                res.  res.                                        spray                                                                Ratio    1:12    1:12    1:15  1:37.9                                                                              1:20  --                                 ______________________________________                                    

                  TABLE XI                                                        ______________________________________                                        Examples 42- 43                                                               Component          42      43                                                 ______________________________________                                        TMAH               0.96    0.96                                               Morpholine         14.4    --                                                 DMAP               --      14.4                                               H.sub.2 O          84.64   84.64                                              Total %            100.00  100.00                                             Development Mode   I       I                                                  mJ/cm.sup.2        --      --                                                 Result             rough;  good;                                                                 no res. no res.                                            Ratio              15:1    15:1                                               ______________________________________                                    

We claim:
 1. A method for developing an image-wise exposed quinonediazide positive-working photoresist without forming irregular depositson the edges of unexposed portions of said photoresist, comprising thesteps of:A. providing said exposed photoresist; B. providing a developercomposition consisting essentially of an aqueous solution of at leastone tetraalkylammonium hydroxide, present in an amount effective toenable said composition to develop said photoresist; and at least oneadjunct having a structure selected from the group consisting of##STR3## wherein n is 0 or 1; m is 1 or 2; each R¹ and R² isindependently selected from hydrogen, methyl, or ethyl, but in StructureI the two R² 's are not both ethyl; and the weight ratio of said primaryalkali to said adjunct is less than about 1:3; C. developing saidphotoresist with said developer until the exposed portions of saidphotoresist are cleared; and D. rinsing said developer from saidphotoresist.
 2. The method of claim 1, wherein said step C is immersiondevelopment.
 3. The method of claim 1, wherein said step C is spraydevelopment and said ratio is less than about 1:9.
 4. A method fordeveloping an image-wise exposed quinone diazide positive-workingphotoresist without forming irregular deposits on the edges of unexposedportions of said photoresist, comprising the steps of:A. providing saidexposed photoresist; B. providing a developer composition consistingessentially of an aqueous solution of a tetraalkylammonium hydroxidepresent in an amount effective to enable said composition to developsaid photoresist; and an alkanolamine having the following structure:##STR4## wherein n is zero or one, each R is independently selected fromhydrogen, methyl, or ethyl, and the weight ratio of saidtetraalkylammonium hydroxide to said alkanolamine is less than about1:3; C. developing said photoresist with said developer until theexposed portions of said photoresist are cleared; and D. rinsing saiddeveloper from said photoresist.
 5. The method of claim 4, wherein saidstep C is immersion development.
 6. The method of claim 4, wherein saidstep C is spray development.
 7. The method of claim 4, wherein saidalkanolamine is 1-amino-3-hydroxypropane.
 8. A method for developing animage-wise exposed quinone diazide positive-working photoresist in amanner providing a C_(p) value of at least about 1.33, comprising thesteps of:A. providing said exposed photoresist; B. providing a developercomposition consisting essentially of an aqueous solution of at leastone tetraalkylammonium hydroxide, present in an amount effective toenable said composition to develop said photoresist; and at least oneadjunct having a structure selected from the group consisting of:##STR5## wherein n is 0 or 1; m if 1 or 2; each R¹ and R² isindependently selected from hydrogen, methyl, or ethyl, but in StructureI the two R² 's are not both ethyl; and the weight ratio of saidtetraalkylammonium hydroxide to said adjunct is less than about 1:3; C.developing said photoresist with said developer until the exposedportions of said photoresist are cleared; and D. rinsing said developerfrom said photoresist.
 9. The method of claim 8, wherein said C_(p)value is at least about 1.33 when said exposed photoresist thickness is1.3 microns plus or minus 0.1 microns; the exposure energy used toexpose said photoresist is from 150 to millijoules per squarecentimeter; the soft bake temperature for said photoresist is from 110°C. to 120° C.; the temperature of said developer is 19° C., plus orminus 1° C.; and the tool used to expose said photoresist is focused onthe upper surface of said photoresist, plus or minus 1 micron.
 10. Themethod of claim 8, wherein said step C is spray development and saidratio is less than about 1:9.
 11. A method for developing an image-wiseexposed quinone diazide positive-working photoresist in a mannerproviding a C_(p) value of at least about 1.33, comprising the stepsof:A. providing said exposed photoresist; B. providing a developercomposition consisting essentially of an aqueous solution of atetraalkylammonium hydroxide present in an amount effective to enablesaid composition to develop said photoresist; and an alkanolamine havingthe following structure: ##STR6## wherein n is zero or one, each R isindependently selected from hydrogen, methyl, or ethyl, and the weightratio of said tetraalkylammonium hydroxide to said alkanolamine is lessthan about 1:3; C. developing said photoresist with said developer untilthe exposed portions of said photoresist are cleared; and D. rinsingsaid developer from said photoresist.
 12. The method of claim 11,wherein said C_(p) value is at least about 1.33 when said exposedphotoresist thickness is 1.3 microns plus or minus 0.1 microns; theexposure energy used to expose said photoresist is from 150 to 250millijoules per square centimeter; the soft bake temperature for saidphotoresist is from 110° C. to 120° C.; the temperature of saiddeveloper is 19° C., plus or minus 1° C.; and the tool used to exposesaid photoresist is focused on the upper surface of said photoresist,plus or minus 1 micron.